WEDNESDAY, March 13 (HealthDay News) -- Adding to the list of "really annoying things," new research is pointing the finger at a technology that can turn public spaces into private misery for many: cellphones.

The study suggests that cellphone calls, and the half-conversations listeners are forced to overhear, are a much more distracting form of background noise than an in-person exchange between two people.

"I find cell phones annoying, frankly, and there's lots of research suggesting that many people agree -- so I wanted to study this," said study lead author Veronica Galvan, an assistant professor in the department of psychological sciences with the College of Arts and Sciences at the University of San Diego.

"What we found," Galvan said, "was that there does seem to be something unique about a one-sided cell conversation that makes it more distracting for people to overhear than a two-way conversation."

Galvan and her colleagues published their findings in the March 13 issue of the journal PLoS ONE.

According to the authors, in 2012 wireless device users worldwide devoted more than 2.3 trillion minutes to cellphone calls, texting, listening to music and Web surfing. Many of the calls are being placed in public spaces such as restaurants, elevators or on public transport.

Last year, a study conducted by researchers at Cornell University asked college students to try to ignore sound recordings while trying to complete a task. Their conclusion: Recordings of one-sided cell phone conversations were actually more distracting, irritating and taxing to the brain than two-sided in-person conversations.

The newer study builds on that work, using a real-world study design. This time, Galvan's team had nearly 150 undergraduate students complete a word-play reading exercise.

There was a hitch, though: Participants were exposed to one of two types of live conversations, either an in-person exchange between two people or a one-sided cellphone call.

In both cases, the exchange was scripted to focus on the same range of topics, including shopping for furniture, details concerning a birthday party for Dad, or meeting up with a date in a shopping mall.

Conversations were similar in length and were overheard by the participants just once, as they struggled to compete the word task. When the conversations ceased, the students were asked to complete memory recall tests, as well as distraction questionnaires.

While all the participants fared comparably well on the tasks, one-sided cellphone conversations were deemed to be "significantly" more distracting than two-sided conversations. Attention seemed to stray more to the one-sided calls, since people who had overheard a one-sided cellphone conversation were more able to recall what had been said versus those who had overheard a two-party exchange.

According to the researchers, people appear to be less able to tune out cellphone conversations compared to two-person exchanges. This supports notions that overheard cellphone jabber might negatively affect a person's ability to concentrate and focus, they said.

Galvan said it remains unclear exactly why this is so.

"We didn't study why cellphone conversations are more distracting," she noted. "But there's a lot of research that shows that [mental] multitasking isn't really possible. That your brain actually has to switch back and forth between listening in and doing something else, rather than doing both tasks at the same time."

"And it also could be a question of control," Galvan added. "Bystanders to these conversations lack any control over whether someone in public answers their phone and shares personal information the bystander doesn't really want to hear. And that lack of control could be stressful. Of course that could be true of a two-way conversation too. So we'll need more research to try and figure this out."

For her part, Lauren Emberson, the lead author of the 2012 study and now a postdoctoral associate in the department of brain and cognitive sciences at the University of Rochester, said the findings were "not surprising."

"I think it's important to know that this is not about people eavesdropping," she said. "Our brains are just naturally drawn to things we know less about that are informationally rich and spark our curiosity. It really is beyond people's control."

Her advice? "I think this work speaks to etiquette," she said. As "people become more aware of the issue, there will be more and more pressure for people not to make calls in a public space where people can't escape."

Evolving technology may even offer at least a partial solution, Emberson said.

"People are using their phones more and more for texting, rather than talking, so while this will probably always be relevant it might actually become less of a problem. But maybe I'm just an optimist."

SOURCES: Veronica V. Galvan, Ph.D., assistant professor, department of psychological sciences, College of Arts and Sciences, University of San Diego; Lauren Emberson, Ph.D., postdoctoral associate, department of brain and cognitive sciences, University of Rochester, New York; March 13, 2013, PLoS ONE